Themed menus: Implement the cutlist editor menus. Refs #11533

Provides an implementation of the main cutlist editor menu
(menu_cutlist.xml), and the exit dialog menu (menu_cutlist_exit.xml).

There is a slight change in behavior - pressing SELECT within a cut
region brings up the entire cutlist menu, rather than a subset.  The
original code suppresses the submenu entry at the end on the SELECT
action.  The original behavior could be restored by adding a third
cutlist menu, or by designing a way to pass extra state to the menu
builder.

To make this work seamlessly with existing action handlers, clumsy
action names like DIALOG_CUTPOINT_NEWCUT_0 are preserved.  This will
need some cleanup.

There is one remaining cutlist-related menu that could be implemented
- the "already editing" dialog.